Or, you know, remove the DoTs from the class, make fester just always hit for 400 (if we were keeping fester at this point), and make ruin come in swinging for 270, since 70 potency happens to be the potency damage of the DoTs if you average it over 12 GCDs. Granted this is conveniently ignoring the various phase changes or even hard casting of DoTs mechanics that would need to see other spells also raised. There is no mechanic that requires having DoTs that needs to stay that way, otherwise classes like Machinist literally could not exist. The devs made a conscious choice to keep the DoTs instead of expunging them. And don't get me started on how godawful Ruination is to the current SMN rotation. 75% uptime, but 20 seconds of that is GUARANTEED to happen during a section where you gain no benefit from it, and there is no practical way to realistically mitigate that without heavy amounts of micro and perfect timing to delay when you recast it, which costs more damage anyways since you'd have to cast more normal DoTs to keep everything lined up.
I'd just like to point out that there is absolutely nothing about DoTs being on the class that makes the class innately more, or less, mobile. The only things that affect mobility are range and whether you have cast times or not. Ranged DPS are innately more mobile than melee because if a boss zones out melee, they lose a lot of damage while the rDPS just ignores the boss movement. Casters are innately the least mobile, but SMN used to be the most mobile because it would cost them 20 potency to instant cast, they had 15s of guaranteed mobility every minute, and a further 20 seconds of optimized mobility every 2 minutes. That has since been taken away which is why the class feels so much less mobile, especially because SMNs cannot let the DoTs lapse anymore or they lose substantially more damage.